What Is a Canonical URL? Definition
The preferred URL of a page that Google should index, which prevents duplicate content.
What is a canonical URL?
A canonical URL is the version of a web page that you prefer Google to index. You define it with the HTML tag <link rel="canonical">.
Example: an online shop's category page can be reached at example.ch/shoes/ and, from a newsletter, at example.ch/shoes/?utm_source=newsletter. Both versions carry <link rel="canonical" href="https://example.ch/shoes/">, so Google knows which URL to index.
Why do canonical URLs matter?
Websites often have several URLs that show the same content (for example with and without www, or with tracking parameters). Without a canonical tag, Google may treat them as duplicate content and split the ranking strength between them.
- Prevents duplicate content – consolidates the ranking signals on one URL
- Protects against content theft – tells Google which page is the original source
- Improves crawl efficiency – Google prefers to crawl the canonical version
Canonical tags are part of every technical SEO review. Our technical SEO checklist shows how they fit in with the other checks.
Frequently asked questions
What is a canonical URL?
A canonical URL is the version of a web page that you prefer Google to index. You define it with the HTML tag link rel="canonical".
Why do canonical URLs matter for SEO?
Without a canonical tag, Google may treat several URLs with the same content as duplicate content and split the ranking strength. The canonical consolidates the signals on one URL.
What is an example of a canonical URL?
A shop page is reachable at example.ch/shoes/ and at the same address with a newsletter tracking parameter. Both versions point to example.ch/shoes/ as the canonical URL.